A method, system and medium for identifying isolated grid operation of distributed power supply

Abstract

The present invention discloses a method for identifying the isolated operation of distributed power sources, comprising the following steps: obtaining power grid data, if the power grid data is target data, after waiting for a preset delay, performing topological analysis on the power grid to divide the electrical island, wherein the electrical island includes a connected substation bus and / or bus and / or circuit breaker; traversing each electrical island, if there is an access point circuit breaker of a distributed power source in the electrical island and there is no substation bus, searching for a bus connected to the access point of the distributed power source in the electrical island, and if the bus voltage is less than a preset threshold, sending a trip command to the access point circuit breaker. The present invention can accurately identify the isolated operation of distributed power sources in the power grid and eliminate risks in a timely manner.

Description

Technical Field

[0001] The present invention relates to the field of power control, and in particular to a method, system and medium for identifying isolated grid operation of distributed power sources. Background Art

[0002] At present, a large number of distributed power sources have been integrated into the main power grid, including small hydropower stations, wind power and photovoltaic power, which has led to changes in the magnitude, direction and distribution of fault currents in the distribution network, and changed the fault characteristics of some power supply areas, which may affect the correct action of protection, fault isolation and post-fault recovery. Figure 1 As shown, node 1 is a distributed power access point, and circuit breaker 506 is an access point circuit breaker. There are two main network power supplies associated with it. When the main network power supply trips due to a fault, the distributed power supply becomes an isolated network. If the isolated network operation of the distributed power supply cannot be identified in time and cut off, it may cause the protection device to fail to reclose, and the station control such as the backup automatic switch will fail, which will eventually endanger the power supply reliability of the system.

[0003] The D5000 system currently used in power dispatching can obtain real-time grid parameters such as the status of each circuit breaker, the status of each disconnector, voltage, current, power flow, etc. in the power grid, and can obtain the location and quantity of various distributed power sources in the access area power grid. However, it lacks the function of identifying whether the distributed power source is operating in an isolated grid and executing corresponding protection measures.

[0004] Therefore, it is necessary to study the method of identifying isolated grid operation after distributed generation is connected to the grid and propose corresponding protection measures. Summary of the invention

[0005] The technical problem to be solved by the present invention is as follows: In view of the above-mentioned problems in the prior art, a method, system and medium for identifying the isolated operation of distributed power sources are provided, which can accurately identify the isolated operation of distributed power sources in the power grid and eliminate risks in a timely manner.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for identifying isolated grid operation of distributed power sources comprises the following steps:

[0008] Acquire power grid data, and if the power grid data is target data, after waiting for a preset delay, perform topological analysis on the power grid to divide electrical islands, wherein the electrical islands include connected substation buses and / or buses and / or circuit breakers;

[0009] Traverse each electrical island, if there is an access point circuit breaker of a distributed power source in the electrical island and there is no substation bus, search for a bus in the electrical island that is connected to the access point of the distributed power source, if the bus voltage is less than a preset threshold, send a trip command to the access point circuit breaker.

[0010] Furthermore, performing topological analysis on the power grid to divide the electrical islands includes the following steps:

[0011] Obtain the configuration information of the access points and access point circuit breakers corresponding to all distributed power sources, obtain the preset power grid model data, and obtain the power grid data in real time;

[0012] According to the power grid model data, a preset search algorithm is used to start searching from the access point circuit breaker, and the electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary.

[0013] Furthermore, the method further includes the step of pre-configuring the power node model, specifically including:

[0014] Obtain configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain preset power grid model data;

[0015] Set all circuit breakers and disconnectors in the power grid model to a closed state, use a preset search algorithm to start searching from the access point circuit breaker, record the circuit breaker, line and transformer information on the search path, until the corresponding substation bus is found, and establish a path corresponding to the access point circuit breaker;

[0016] A power node model is established based on the path information corresponding to all distributed power sources.

[0017] Furthermore, the search algorithm is a depth-first search algorithm.

[0018] Furthermore, performing topological analysis on the power grid to divide the electrical islands includes the following steps:

[0019] Obtain the configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain power grid data in real time;

[0020] According to the power node model, the substation bus is searched from the access point circuit breaker along the corresponding path in the power node model, and the electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary.

[0021] Further, judging the electrical island boundary according to the power grid data specifically includes:

[0022] If the circuit breaker or disconnector connected to the same bus is open, the corresponding circuit breaker or disconnector is used as the electrical island boundary, otherwise the search continues along the circuit breaker or disconnector;

[0023] If the active power direction of the line endpoint or transformer winding connected to the same bus is negative, the search continues along the line or transformer, otherwise the line endpoint or transformer winding is taken as the electrical island boundary;

[0024] If a substation bus is found, the substation bus is used as the electrical island boundary;

[0025] If the path is searched completely within the boundary of the electrical island, the search is stopped and the information of the busbar and / or line and / or transformer and / or circuit breaker and / or disconnector is recorded.

[0026] Furthermore, the power grid data includes current and active power of transformer windings, current and active power of AC line segment endpoints, current and active power of circuit breakers, current and active power data of loads, bus voltage data, circuit breaker switch status data, and disconnector status data.

[0027] Furthermore, the steps of displaying the power node model are also included, including:

[0028] Get the initial layout of the power node model to be displayed, randomly select two targets SUB1 and SUB2, exchange the coordinates of SUB1 and SUB2, calculate the Manhattan distance d, traverse all targets, and obtain the total Manhattan distance D;

[0029] The objective function value is calculated based on the preset weight factor Ψ and the total Manhattan distance D. The expression is as follows:

[0030] F=P+ΨD

[0031] In the above formula, P is the total number of intersections in the initial layout, D is the total Manhattan distance, and Ψ is the weight factor;

[0032] The power node model to be displayed is rearranged according to the objective function.

[0033] The present invention also proposes a distributed power supply isolated grid operation identification system, comprising:

[0034] An electrical island division unit is used to obtain power grid data, and if the power grid data is target data, after waiting for a preset delay, perform topological analysis on the power grid to divide the electrical island, wherein the electrical island includes connected substation buses and / or busbars and / or circuit breakers;

[0035] The isolated grid operation judgment unit is used to traverse each electrical island. If there is an access point circuit breaker of a distributed power source in the electrical island and there is no substation bus, the bus connected to the access point of the distributed power source in the electrical island is searched. If the bus voltage is less than a preset threshold, a trip command is sent to the access point circuit breaker.

[0036] The present invention also proposes a computer-readable storage medium, which stores a computer program programmed or configured to execute any of the methods for identifying isolated grid operation of distributed power sources.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The present invention divides the power grid into electrical islands by topological analysis based on the idea of ​​regional division, and searches for distributed power sources that meet the conditions for isolated grid operation for each electrical island, thereby simplifying the calculation complexity, and using the voltage of the bus at the access point of the distributed power source as an auxiliary judgment basis to avoid the occurrence of false operations and avoid complex calculations and logical judgments.

[0039] 2. The analysis object of the present invention is only the power grid data acquired in real time, which reduces the occupation of system resources and ensures that the data source is simple and reliable.

[0040] 3. The processing method of the present invention after the isolated network is identified is to send a tripping command, without adding other equipment for subsequent processing, thus saving economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of distributed generation nodes in the power grid.

[0042] Figure 2 Schematic diagram of the electrical island division.

[0043] Figure 3 This is an overall flow chart of the identification method in Embodiment 1 of the present invention.

[0044] Figure 4 This is an algorithm flow chart of the identification method in Embodiment 1 of the present invention.

[0045] Figure 5 This is a flow chart of establishing a power node model in the first embodiment of the present invention.

[0046] Figure 6 This is a flow chart of analyzing the main power supply path of a distributed power source in the first embodiment of the present invention.

[0047] Figure 7 This is a schematic diagram of the result of topological analysis and division of electrical islands in the power grid in the first embodiment of the present invention.

[0048] Figure 8This is a general architecture diagram of the system in Embodiment 2 of the present invention.

[0049] Fig. 9 This is a diagram of the system hardware architecture in Embodiment 2 of the present invention.

[0050] Fig.10 This is a diagram of the system software architecture in Embodiment 2 of the present invention.

[0051] Fig.11 This is a diagram of the system functional architecture in Embodiment 2 of the present invention.

[0052] Fig.12 This is a diagram of the system interface in the second embodiment of the present invention.

[0053] Fig.13 This is a flow chart showing the system power node model in the second embodiment of the present invention.

[0054] Fig.14 This is a diagram of the system power node model interface in the second embodiment of the present invention.

[0055] Fig.15 This is a diagram of the system isolated network identification result interface in the second embodiment of the present invention. DETAILED DESCRIPTION

[0056] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0057] Embodiment 1

[0058] Under ideal operating conditions, all substation buses, busbars, and circuit breakers in the entire power grid are connected. We call the area where a substation bus and / or busbars and / or circuit breakers are connected an electrical island. In an ideal state, the entire power grid is a large electrical island. However, in reality, due to accidents, maintenance, misoperation, sneak tripping and other factors, the circuit breaker may be tripped, and the power grid may be split into multiple electrical islands, such as Figure 2 As shown in the figure, the circuit breakers zhouyu 502, haoyuchen 502, bai 508 and circuit breaker 300 are opened to disconnect the corresponding power supply links. Figure 2 The power grid is divided into electrical island A and electrical island B. The circuit breakers Zhou Yu 502, Hao Yu Chen 502 and circuit breaker 300 in electrical island B are each independent electrical islands. The divided electrical islands are beneficial to reducing the computational complexity of distributed power source isolated grid operation identification.

[0059] Therefore, if Figure 3 As shown, this embodiment proposes a method for identifying isolated grid operation of distributed power sources, comprising the following steps:

[0060] S1) acquiring power grid data, and if the power grid data is target data, after waiting for a preset delay, performing topological analysis on the power grid to divide the electrical island, wherein the electrical island includes connected substation busbars and / or busbars and / or circuit breakers;

[0061] S2) traverse each electrical island, if there is a distributed power access point circuit breaker in the electrical island and there is no substation bus, search for the bus connected to the access point of the distributed power source in the electrical island, if the bus voltage is less than a preset threshold, send a trip command to the access point circuit breaker.

[0062] Specifically, Figure 4 As shown, the algorithm flow from step S1) to step S2) before sending a trip command to the access point circuit breaker is as follows:

[0063] (1) Read the change message from D5000 through the message bus interface;

[0064] (2) Determine whether the change message is a circuit breaker position change or a disconnector opening. If yes, proceed to the next step; otherwise, return to step (1);

[0065] (3) Delay for 5 seconds, waiting for the reclosing, backup automatic switching and other automatic devices to operate;

[0066] (4) performing network topology analysis based on a preset power grid model and the real-time data obtained in step (1) to divide electrical islands;

[0067] (5) Determine the number of electrical islands. If the number of energized electrical islands is greater than 1, proceed to the next step; otherwise, return to step (1);

[0068] (6) Select an electrical island;

[0069] (7) Determine whether there is a circuit breaker at the access point of the distributed power source in the electrical island. If so, proceed to the next step.

[0070] (8) Continue to determine whether there is a 220kV substation bus inside the electrical island. If so, it means that the distributed power source is not operating in an isolated grid. Return to step (6) to continue to determine the next electrical island. If not, proceed to the next step.

[0071] (9) Search for the bus connected to the circuit breaker at the access point of the distributed generation, and read the voltage of the bus from D5000. If the voltage is lower than the threshold value, it means that the distributed generation is operating in an isolated grid and the voltage is unqualified, and the isolated grid operation identification result is given.

[0072] In this embodiment, in order to determine the access point of the distributed power source, the step of pre-configuring the power source node model is also included before step S1), which specifically includes:

[0073] Obtain configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain preset power grid model data;

[0074] Set all circuit breakers and disconnectors in the power grid model to a closed state, use a preset search algorithm to start searching from the access point circuit breaker, record the circuit breaker, line and transformer information on the search path, until the corresponding substation bus is found, and establish a path corresponding to the access point circuit breaker;

[0075] A power node model is established based on the path information corresponding to all distributed power sources.

[0076] In this embodiment, the search algorithm adopts a depth-first search algorithm. Specifically, in this embodiment, according to the pre-configured number of distributed power access nodes and access point circuit breaker data, based on the preset power grid model data and operation data in D5000, the search starts from the access point circuit breaker, and the main grid power path associated with the access point circuit breaker is automatically retrieved in the D5000 system power grid topology using the depth-first search algorithm. The main grid power source of each node is found, and the 110kV bus reaching the 220kV substation is terminated, and the power supply model of each node is automatically established.

[0077] Specifically, Figure 5 As shown in the figure, the process of configuring the power node model is as follows:

[0078] (1) First, read the configuration data of the distributed power source and the access point circuit breaker;

[0079] (2) Reading grid model data and real-time operation data from D5000 through the interface;

[0080] (3) Since we are analyzing the power node model, we assume that all circuit breakers and disconnectors are in the closed state;

[0081] (4) Based on the grid topology connection, the depth-first search algorithm is used to start the search from the access point circuit breaker, and the circuit breaker, line and main transformer information on the search path is recorded until the 110 kV bus of the 220 kV substation is found;

[0082] (5) After the search is completed, a power node model is established based on the search path information.

[0083] For the node 2 to be identified in the electrical island B, since the electrical island B still contains a large number of substation buses, busbars and circuit breakers, we need to consider further subdividing it. The power grid is usually operated in an open loop, so at any time there is only one main power supply associated with each distributed power access node, and the other power supplies are in standby mode. By judging the position status and power flow direction of each circuit breaker in the power node model, the current power supply link of each node can be retrieved, and the boundary of the electrical island can be determined according to the position status of each circuit breaker and the power flow direction. In this embodiment, the topological analysis of the power grid to divide the electrical island includes the following steps:

[0084] Obtain the configuration information of the access points and access point circuit breakers corresponding to all distributed power sources, obtain the preset power grid model data, and obtain the power grid data in real time;

[0085] According to the power grid model data, a preset search algorithm is used to start searching from the access point circuit breaker, and the electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary.

[0086] Specifically, Figure 6 As shown, the specific process of retrieving the current power supply link of each node is as follows:

[0087] (1) First, read the configuration data of the distributed power source and the access point circuit breaker;

[0088] (2) Reading grid model data and real-time operation data from D5000 through the interface;

[0089] (3) Based on the grid topology connection, use the depth-first search algorithm to start the search from the access point circuit breaker. If the active power direction of the line endpoint or transformer winding connected to the same logical bus is negative, continue searching along the line or transformer. If the active power direction of the line endpoint or transformer winding is positive, stop searching from the line or transformer, record the circuit breaker, line and main transformer information on the search path, and stop searching until the 110kV bus of the 220kV substation is found;

[0090] (4) After the search is completed, a main power supply path model of plant-line-circuit breaker is established based on the search path information.

[0091] In this embodiment, performing topological analysis on the power grid and dividing the electrical islands includes the following steps:

[0092] Obtain the configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain power grid data in real time;

[0093] According to the power node model, the substation bus is searched from the access point circuit breaker along the corresponding path in the power node model, and the electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary.

[0094] In this embodiment, determining the electrical island boundary according to the power grid data specifically includes:

[0095] If the circuit breaker or disconnector connected to the same bus is open, the corresponding circuit breaker or disconnector is used as the electrical island boundary, otherwise the search continues along the circuit breaker or disconnector;

[0096] If the active power direction of the line endpoint or transformer winding connected to the same bus is negative, the search continues along the line or transformer, otherwise the line endpoint or transformer winding is taken as the electrical island boundary;

[0097] If a substation bus is found, the substation bus is used as the electrical island boundary;

[0098] If the path is searched completely within the boundary of the electrical island, the search is stopped and the information of the busbar and / or line and / or transformer and / or circuit breaker and / or disconnector is recorded.

[0099] like Figure 7 As shown, according to the method of performing topological analysis on the power grid and dividing the electrical islands in this embodiment, Figure 2 The entire power grid is further subdivided into electrical island A, electrical island B, electrical island C, and electrical island D, and electrical island B is further subdivided into three electrical islands, so as to facilitate the rapid determination of the electrical islands where there are access point circuit breakers of distributed power sources and no substation busbars in step S2), and to perform isolated grid operation identification.

[0100] In this embodiment, the power grid data includes the current and active power of the transformer winding, the current and active power of the AC line segment endpoints, the current and active power of the circuit breaker, the current and active power of the load, the bus voltage data, the circuit breaker switch status data, and the disconnector status data.

[0101] In this embodiment, the step of displaying the power node model is also included, which specifically includes:

[0102] Get the initial layout of the power node model to be displayed, randomly select two targets SUB1 and SUB2, exchange the coordinates of SUB1 and SUB2, calculate the Manhattan distance d, traverse all targets, and obtain the total Manhattan distance D;

[0103] The objective function value is calculated based on the preset weight factor Ψ and the total Manhattan distance D. The expression is as follows:

[0104] F=P+ΨD

[0105] In the above formula, P is the total number of intersections in the initial layout, D is the total Manhattan distance, and Ψ is the weight factor;

[0106] The power node model to be displayed is rearranged according to the objective function.

[0107] This embodiment also provides a distributed power supply isolated grid operation identification system, including:

[0108] An electrical island division unit is used to obtain power grid data, and if the power grid data is target data, after waiting for a preset delay, perform topological analysis on the power grid to divide the electrical island, wherein the electrical island includes connected substation buses and / or busbars and / or circuit breakers;

[0109] The isolated grid operation judgment unit is used to traverse each electrical island. If there is an access point circuit breaker of a distributed power source in the electrical island and there is no substation bus, the bus connected to the access point of the distributed power source in the electrical island is searched. If the bus voltage is less than a preset threshold, a trip command is sent to the access point circuit breaker.

[0110] This embodiment also provides a computer-readable storage medium, which stores a computer program programmed or configured to execute any of the methods for identifying isolated grid operation of distributed power sources.

[0111] Embodiment 2

[0112] This embodiment proposes a distributed power supply isolated grid operation identification system based on the first embodiment, which is developed based on the D5000 platform, obtains power grid model data and power grid operation data by calling the real-time library service and commercial library service of the D5000 platform, and obtains the telesignaling and telemetry change data of the power grid by calling the message bus service. The automatic removal of the circuit breaker at the access point of the distributed power supply during the isolated grid operation is realized through the D5000 remote control interface.

[0113] like Figure 8 As shown, in this embodiment, the regional power grid distributed power supply isolated network operation identification system shares the server of the D5000 platform in hardware, without additional investment. The operating system can use the domestic Kirin or Ningsi operating system, and the database shares the D5000 platform's DAMO database, and the relevant tables of this project are added to the D5000 database. The middleware uses GraphViz to realize the automatic mapping of power node models and power supply paths. The application and display mainly realize the functions of power node model analysis, power supply path analysis, automatic identification and removal of isolated networks, etc., and realizes the visualization of power node models and power supply path diagrams based on SVG format through QwebView.

[0114] like Fig. 9As shown in the figure, the distributed power supply isolated grid operation identification module is deployed in the safety zone I, in the same network as the D5000 platform, and shares the services provided by the database server and SCADA server of the D5000 platform. The background program can be deployed on the SCADA server, or on a separate isolated grid operation identification and removal application server. As a workstation of the D5000 system, the server can obtain the D5000 power grid model, real-time data, change data, and remote control interface through the services provided by the D5000.

[0115] The database uses the domestically produced DAMO database to realize the identification of isolated network operation and the storage of historical data.

[0116] The workstation can share the existing dispatcher workstation, or deploy a new workstation as a workstation of the D5000 system. The isolated network operation identification and removal software front-end display software can be run on the workstation. The dispatcher can browse the power node model of the distributed power source, the power supply path, and the historical records of isolated network identification and removal.

[0117] like Fig.10 As shown in the figure, the software architecture adopts C / S architecture, and C++ / QT is mainly used to realize the development of server and client software functions. The entire software consists of basic support layer, platform support layer and application layer.

[0118] 1) Basic support layer. The basic support layer is the hardware equipment and network platform that supports the entire platform. It establishes a complete network system, security system, storage system, system basic software and other systems to provide efficient and flexible support services for the platform support layer and application layer. The operating system can support domestic Kylin operating system and Ningsi operating system, and the database supports domestic databases such as DAMO and Jincang, which are mainly used to store business data of various business functions and analysis and statistical results data.

[0119] 2) Platform support layer: The platform support layer consists of a public service layer and middleware. The public service layer mainly provides real-time library access services, commercial library access services, message bus services, and remote control interface services provided by the D5000 platform. The middleware mainly uses GraphViz and Websocket. GraphViz is mainly used to realize the automatic drawing function, and websocket is mainly used to realize the data interaction function between the front and back ends.

[0120] 3) Application layer: Based on the basic support layer and platform support layer, the application layer uses C++ / Qt to develop the application functions of this project. The background program implements network topology program, power node model search, power supply path search, distributed power supply isolated network operation, isolated network access point circuit breaker removal and other functions, and the front-end human-computer interaction program implements distributed power supply access point circuit breaker configuration, automatic power supply path mapping display, automatic power model mapping display, isolated network identification and removal log browsing and other functions.

[0121] like Fig.11 As shown, the distributed power supply isolated grid operation identification module consists of four major functions: data access, distributed power supply network topology analysis, distributed power supply isolated grid identification and removal, and human-machine interface display.

[0122] The data access functions include grid model data access, grid operation mode data access and grid change data access.

[0123] Distributed power network topology analysis includes the power node model topology analysis of distributed power and the main power supply path analysis of distributed power.

[0124] The human-machine interface display functions include home page display, distributed power supply node model display, distributed power supply main power supply path display, isolated grid operation identification and removal log browsing, and access point circuit breaker configuration.

[0125] The power grid model data of this embodiment needs to be accessed from the D5000 platform, including voltage type table, power company table, region table, plant station table, interval table, circuit breaker table, switch table, ground switch table, busbar table, generator set table, load table, T AC line table, AC line segment table, AC line segment endpoint table, transformer table, transformer winding table, shunt capacitor / reactor table, series compensator table, single-ended component table, etc. The access method is to read through the real-time library access interface provided by D5000. The access cycle is to read the power grid model data from D5000 once every hour.

[0126] The real-time power grid data of this embodiment needs to access the real-time operation data including telemetry data and telesignaling data from the D5000 platform. Telemetry data includes the current and active power of transformer windings, the current and active power of AC line segment endpoints, the current and active power of circuit breakers, the current and active power of loads, bus voltage data, etc. Telesignaling data includes circuit breaker switch status data, disconnector status data, and grounding disconnector status data, etc. The access method is to read through the real-time library access interface provided by D5000. The access cycle is to read the real-time operation from D5000 every 5 minutes.

[0127] The change message data of this embodiment needs to be accessed from the D5000 platform, mainly the change telesignaling data. The change telesignaling data includes the circuit breaker switch state change data, the disconnector state change data, the grounding disconnector state change data and the protection signal change data. The access method is to read through the message bus interface of D5000. The access cycle is to receive the change data in real time.

[0128] According to the number of distributed generation access nodes and access point circuit breakers in the system configuration, based on the D5000 power grid model data and operation data, the search starts from the access point circuit breaker, and the depth-first search algorithm is used to automatically retrieve the main network power path associated with the access point circuit breaker in the D5000 system power grid topology, find out the main network power source of each node, and terminate with the 110kV bus reaching the 220kV substation, and automatically establish the power supply model of each node.

[0129] The process of distributed power node model analysis is as follows:

[0130] (1) First, read the configuration data of the distributed generation and access point circuit breakers.

[0131] (2) Read the grid model data and real-time operation data from D5000 through the interface.

[0132] (3) Since we are analyzing the power node model, we assume that all circuit breakers and disconnectors are in the closed state.

[0133] (4) Based on the grid topology connection, a depth-first search algorithm is used to start the search from the access point circuit breaker, and the circuit breaker, line and main transformer information on the search path is recorded until the 110 kV bus of the 220 kV substation is found.

[0134] (5) After the search is completed, a power node model of the plant-line-circuit breaker is established based on the search path information.

[0135] By determining the position status of each circuit breaker and the direction of power flow in the node model, the current power supply link of each node can be retrieved.

[0136] The distributed power supply main power supply path search process is as follows:

[0137] (1) First, read the configuration data of the distributed generation and access point circuit breakers.

[0138] (2) Read the grid model data and real-time operation data from D5000 through the interface.

[0139] (3) Based on the grid topology connection, use the depth-first search algorithm to start the search from the access point circuit breaker. If the active power direction of the line endpoint or transformer winding connected to the same logical bus is negative, continue searching along the line or transformer. If the active power direction of the line endpoint or transformer winding is positive, stop searching from the line or transformer. Record the information of the circuit breaker, line, and main transformer on the search path until the 110kV bus of the 220kV substation is found.

[0140] (4) After the search is completed, a main power supply path model of plant-line-circuit breaker is established based on the search path information.

[0141] When the power grid is in normal operation, the entire grid's live equipment operates as an electrical island, and the distributed power source and its access point circuit breaker are also in this electrical island. During the operation of the power grid, various factors such as accidents, maintenance, misoperation, and sneak tripping may cause the circuit breaker to trip, and the power grid may be split into multiple electrical islands. When the automatic devices such as backup automatic switching and reclosing function correctly, the power grid will resume normal operation. If the automatic device does not function correctly, the distributed power source may operate in an isolated grid. During the operation of the isolated grid, the capacity of the distributed power source cannot guarantee the stable operation of the isolated grid, which will cause the voltage and power flow of the bus connected to the access point circuit breaker to change compared to normal operation. If the access point circuit breaker is not removed in time, it may affect the safe and stable operation of the load. At this time, it is necessary to send a remote control trip command to the access point circuit breaker to remove the circuit breaker.

[0142] The distributed power supply isolated grid identification algorithm process is as follows:

[0143] (1) Read the change message from D5000 through the message bus interface.

[0144] (2) Determine whether the change message is a circuit breaker position change or a disconnector opening. If yes, proceed to the next step.

[0145] (3) Delay for 5 seconds to wait for the reclosing, backup and other automatic devices to operate.

[0146] (4) Conduct network topology analysis based on power grid models and real-time data.

[0147] (5) Determine the number of electrical islands. If the number of energized electrical islands is greater than 1, proceed to the next step.

[0148] (6) Circulating electrical island.

[0149] (7) Determine whether there is a distributed power source and its access point circuit breaker in the electrical island. If so, proceed to the next step.

[0150] (8) Continue to determine whether there is a 220kV substation bus in the electrical island. If so, it means that the distributed power source is not operating in an isolated grid. Continue to determine the next electrical island from (6). If there is no 220kV bus in the electrical island, it means that the distributed power source is operating in an isolated grid. Continue to the next step.

[0151] (9) Search for the bus connected to the circuit breaker at the access point of the distributed generation, and read the voltage of the bus from D5000. If the voltage is lower than the threshold value, it means that the distributed generation is operating in an isolated grid and the voltage is unqualified, and the isolated grid operation identification result is given.

[0152] When the distributed power source is judged to be in isolated grid operation, the isolated grid identification results, access point circuit breakers and remote

[0153] After the system runs stably, the remote control interface of D5000 is called to automatically cut off the access point circuit breaker.

[0154] This embodiment displays the interface as follows Fig.12 As shown, it mainly includes the following functions:

[0155] (1) Map-based display of distributed power sources. The location and name of distributed power sources are roughly displayed on the Changde map. Fig.12 shown.

[0156] (2) Click each distributed power icon to pop up a dialog box showing the power node model and power supply path diagram of the distributed power.

[0157] (3) When the system determines that a distributed power source is operating in an isolated grid, the icon of the distributed power source will flash. Click the icon and it will stop flashing, confirming the event.

[0158] (4) Display the results of the isolated grid operation identification of distributed power sources in a list, including the isolated grid time, the name of the distributed power source, etc.

[0159] (5) Display the real-time change message information of circuit breakers and protections through a list, including the trip time, protection or circuit breaker name.

[0160] like Fig.13 As shown in the figure, the power node model display function automatically generates the SVG file of the power node model diagram based on the power node model search results, using the automatic layout and automatic wiring algorithms of the electrical diagram. It also renders the circuit breaker status of the SVG diagram in combination with real-time operation data, and finally displays the SVG diagram through QwebView.

[0161] In order to place substations on the grid in a given rectangular space so that the distance between substations with line connections is the shortest and the number of line crossings is the smallest, this embodiment uses a random optimization method to first obtain the initial layout of substations in the block, and the strategy for generating a new solution is to randomly select two substations SUB1 and SUB2 in this supply area, exchange the coordinates of SUB1 and SUB2, and recalculate the objective function value. The advantage of the random exchange strategy is that the result of the initial layout will not affect the final optimization result.

[0162] The composite objective function is as follows:

[0163] F=P+ΨD

[0164] Where: P is the total number of intersections, D is the total Manhattan distance, and Ψ is the weight factor.

[0165] The distance between two substations is also expressed by Manhattan distance. That is, there are substation A (x1, y1) and substation B (x2, y2), and the distance between them is d.

[0166] d=|x1-x2|+|y1-y2|

[0167] Total Manhattan distance

[0168] D=∑d

[0169] The final power node model shows the effect as follows Fig.14 shown.

[0170] Similarly, based on the main power supply path analysis results, the electrical diagram automatic layout and automatic wiring algorithm are used to automatically generate the SVG file of the main power supply path diagram. The SVG diagram circuit breaker status is rendered in combination with real-time operation data, and finally the SVG diagram is displayed through QwebView. I will not go into details here.

[0171] like Fig.15 As shown, the isolated network identification result interface in this embodiment has the following functions:

[0172] (1) List view function. Displays the orphan network identification and removal records in descending order of identification time. Supports paging display.

[0173] (2) Query function. You can query historical records by record status, identification time, distributed power source name, etc.

[0174] (3) Export function: The isolated network identification and removal history records can be exported to Excel.

[0175] (4) Confirmation function: When the system automatically identifies the isolated grid operation, you can manually confirm whether the identification result is correct.

[0176] (5) Ignore function. When the system automatically identifies an isolated network, if it is manually judged to be a misidentification, click the Ignore button to ignore the record.

[0177] (6) View the power supply path. Click the View power supply path button to view the main power supply path diagram of the distributed power source in a pop-up window.

[0178] In the D5000 system, distributed power sources are maintained as wind power stations or photovoltaic power stations. A distributed power source may be connected to the Internet through one or more access point circuit breakers. Topologically, the access point circuit breaker is used to achieve the connection with the grid topology. In order to ensure the accuracy of the cut-off switch and avoid the mistaken cut-off switch during the isolated network operation, the isolated network identification result interface can also maintain the association between the distributed power source and the cut-off circuit breaker, with the following functions:

[0179] (1) List view function. The configuration records of distributed power sources and access point circuit breakers can be displayed in a list, including the name of the distributed power source, the online plant station, the online switch, the remote control plant station and the remote control point number.

[0180] (2) Added function. Click the Add button to add a record. Maintain the association between distributed power sources and access point circuit breakers. One distributed power source can be associated with multiple access point circuit breakers.

[0181] (3) Delete function: Click the Delete button to delete a record.

[0182] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for identifying isolated grid operation of distributed power sources, characterized in that: The following steps are involved: Acquire power grid data, the power grid data including current and active power of transformer windings, current and active power of AC line segment endpoints, current and active power of circuit breakers, current and active power of loads, bus voltage data, circuit breaker switch status data, disconnector status data; if the power grid data is target data, after waiting for a preset delay, perform topological analysis on the power grid to divide the electrical island, the electrical island including connected substation busbars and / or busbars and / or circuit breakers; Traversing each electrical island, if there is a circuit breaker at the access point of the distributed power source in the electrical island and there is no substation bus, searching for a bus connected to the access point of the distributed power source in the electrical island, and if the bus voltage is less than a preset threshold, sending a trip command to the circuit breaker at the access point; The topological analysis and division of electrical islands in the power grid includes the following steps: Obtain the configuration information of the access points and access point circuit breakers corresponding to all distributed power sources, obtain the preset power grid model data, and obtain the power grid data in real time; According to the power grid model data, a preset search algorithm is used to start searching from the access point circuit breaker, and an electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary. Determining the electrical island boundary according to the power grid data specifically includes: If the circuit breaker or disconnector connected to the same bus is open, the corresponding circuit breaker or disconnector is used as the electrical island boundary, otherwise the search continues along the circuit breaker or disconnector; If the active power direction of the line endpoint or transformer winding connected to the same bus is negative, the search continues along the line or transformer, otherwise the line endpoint or transformer winding is taken as the electrical island boundary; If a substation bus is found, the substation bus is used as the electrical island boundary; If the corresponding path in the power node model is searched within the boundary of the electrical island, the search is stopped and the bus and / or line and / or transformer and / or circuit breaker and / or disconnector information is recorded.

2. The method for identifying isolated grid operation of distributed power sources according to claim 1, characterized in that: It also includes steps to pre-configure the power node model, including: Obtain configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain preset power grid model data; Set all circuit breakers and disconnectors in the power grid model to a closed state, use a preset search algorithm to start searching from the access point circuit breaker, record the circuit breaker, line and transformer information on the search path, until the corresponding substation bus is found, and establish a path corresponding to the access point circuit breaker; A power node model is established based on the path information corresponding to all distributed power sources.

3. The method for identifying isolated grid operation of distributed power sources according to claim 1 or 2, characterized in that: The search algorithm is a depth-first search algorithm.

4. The method for identifying isolated grid operation of distributed power sources according to claim 2, characterized in that: The topological analysis and division of electrical islands in the power grid includes the following steps: Obtain the configuration information of access points and access point circuit breakers corresponding to all distributed power sources, and obtain power grid data in real time; According to the power node model, the substation bus is searched from the access point circuit breaker along the corresponding path in the power node model, and the electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary.

5. The method for identifying isolated grid operation of distributed power sources according to claim 2, characterized in that: It also includes steps to present a power node model, including: Get the initial layout of the power node model to be displayed, randomly select two targets SUB1 and SUB2, exchange the coordinates of SUB1 and SUB2, calculate the Manhattan distance d, traverse all targets, and obtain the total Manhattan distance D; The objective function value is calculated based on the preset weight factor Ψ and the total Manhattan distance D. The expression is as follows: F=P+ΨD In the above formula, P is the total number of intersections in the initial layout, D is the total Manhattan distance, and Ψ is the weight factor; The power node model to be displayed is rearranged according to the objective function.

6. A distributed power supply isolated grid operation identification system, characterized in that: include: The electrical island division unit is used to obtain power grid data, wherein the power grid data includes current and active power of transformer windings, current and active power of AC line segment endpoints, current and active power of circuit breakers, current and active power data of loads, bus voltage data, circuit breaker switch status data, and disconnector status data. If the power grid data is target data, after waiting for a preset delay, topological analysis is performed on the power grid to divide the electrical island, wherein the electrical island includes connected substation buses and / or buses and / or circuit breakers. Topological analysis of the power grid to divide the electrical island includes the following steps: Obtain the configuration information of the access points and access point circuit breakers corresponding to all distributed power sources, obtain the preset power grid model data, and obtain the power grid data in real time; According to the power grid model data, a preset search algorithm is used to start searching from the access point circuit breaker, and an electrical island boundary is determined according to the power grid data, and then the electrical island is divided according to the electrical island boundary. Determining the electrical island boundary according to the power grid data specifically includes: If the circuit breaker or disconnector connected to the same bus is open, the corresponding circuit breaker or disconnector is used as the electrical island boundary, otherwise the search continues along the circuit breaker or disconnector; If the active power direction of the line endpoint or transformer winding connected to the same bus is negative, the search continues along the line or transformer, otherwise the line endpoint or transformer winding is taken as the electrical island boundary; If a substation bus is found, the substation bus is used as the electrical island boundary; If the search along the corresponding path in the power node model is completed within the boundary of the electrical island, the search is stopped, and the bus and / or line and / or transformer and / or circuit breaker and / or disconnector information is recorded; The isolated grid operation judgment unit is used to traverse each electrical island. If there is an access point circuit breaker of a distributed power source in the electrical island and there is no substation bus, the bus connected to the access point of the distributed power source in the electrical island is searched. If the bus voltage is less than a preset threshold, a trip command is sent to the access point circuit breaker.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program programmed or configured to execute the method for identifying isolated grid operation of distributed power sources according to any one of claims 1 to 5.

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